Feeding of liquid into a liquid cooled, heavy current cable

ABSTRACT

A heavy current cable has an inner tube for some cooling liquid, an outer envelope, and conductors inbetween. A socket connected to the cable end has a body, a sleeve for insertion of the conductor ends, and a tube threaded into the socket body and receiving coolant fluid from a duct through that socket body. The conductors are strapped to that socket tube and feeder tubes communicate with that socket tube and extend radially therefrom with axial continuation to discharge cooling fluid axially, directly into the conductor containing space inbetween inner tube and outer envelope of the cable.

[ Sept. 23, 1975 United States Patent [191 Hiibner FEEDING OF LIQUID INTO A LIQUID WXX 99 4 1.. 7H 144 .77 11 COOLED, HEAVY CURRENT CABLE 1/1974 Goodman 4 1974 174/19 X 4/1974 Kluge et Goodman [75] Inventor: Ernst Hiibner, Osnabruck, Germany Kabel-und Metallwerke [73] Assignee:

Gutehoffnungshutte AG, Hannover, Germany Primary ExaminerArthur T. Grimley Attorney, Agent, or Firm-Ralf H. Siegemund [22] Filed: Oct. 17, 1974 [57] ABSTRACT A heavy current cable has an inner tube for some Appl. No.: 515,517

cooling liquid, an outer envelope, and conductors Foreign Appllcatlun Pl'ml'lty Data inbetween. A' socket connected to the cable end has a Oct. 20, 1973 Germany............................ 2352808 body, a sleeve for insertion of the conductor ends, and

a tube threaded into the socket body and receivin coolant fluid from a duct through that socket bod The conductors are strapped to that socket tube and feeder tubes communicate with that socket tube and 339/112; 219/130 extend radially therefrom with axial continuation to discharge cooling fluid axially, directly into the con- [56] References Cited ductor containing space inbetween inner tube and UN E T ES PATENTS outer envelope of the cable.

2,835,721 5/1958 Leathers........................... 174/19 X 4 Claims, 3 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of2 3,908,073

US Patent Sept. 23,1975 Sheet 2 of2 3,908,073

FEEDING OF LIQUID INTO A LIQUID COOLED, HEAVY CURRENT CABLE BACKGROUND OF THE INVENTION The present invention relates to liquid cooled high power cable, particularly of the heavy current type. used to apply power to electrical arc melting furnaces.

Heavy current cable with liquid cooling are comprised for example, of an inner tube through which passes the coolant, and conductors, possibly of the stranded variety, are disposed on that tube. This partic ular assembly is jacketed in a tubular envelope or hose. The ends of such a cable are connected to a socket which serves also as connector for the liquid coolant.

Steel scrap, sponge iron and prereduced iron ore is often melted in such are furnaces fed with electric current from suitable power supply sources, e.g., transformers via water cooled cables. Cooling protects the cable against the rather heavy electric current. Aside from being capable of conducting high current, such cable must also withstand high outside temperature and will undergo significant mechanical wear and loads.

The US. Pat. No. 3,551,581 discloses a flexible cable for heavy current having an inner tube for passing cooling water and an outer envelope as mechanical protection; the conducts are disposed between tube and envelope. The inner tube is perforated over its entire length to permit water to flow also around the conductors on the outside of the tube (but, of course, inside of the envelope). Additionally, the tube has axial ribs separating and insulating the individual conductors from each other.

Unfortunately, cooling of the conductors is not well defined with such an arrangement. Rather, cooling depends on a more or less random flow pattern as between the interior of the tube and the axially partitioned space on the outside holding the conductors. Additionally, the inner tube is made from sections with throttles interposed at the section joints to impede the flow of coolant and force it through the perforations.

It is also known to provide a receiving tube which is inserted in a socket and receives the inner tube of the cable, while coolant flow is forced from the socket into the inner tube and from there to the conductors (see German printed patent application No. 2,212,244).

DESCRIPTION OF THE INVENTION It is an object of the present invention to improve the conduction of coolant from a cable socket to the conductors of the cable in a heavy current type cable.

It is a specific object of the invention to improve the cooling of heavy current cable having an inner tube, an outer tube and conductors in the annular space between the tubes.

In accordance with the preferred embodiment of the present invention, it is suggested to provide for multiple feeder tubes between a duct in a cable socket and the annular, cylindrical or ring space between inner and outer tubes of a cable, to feed coolant in axial flow directly into that space and inbetween the conductors contained therein. This direct feeding of coolant to the conductors intensifies cooling and definiteness of cooling conditions for the conductors which in turn, extends life and operative reliability of the cable.

In furtherance of the invention, a particular tube is threaded into the socket and communicates directly with a duct therein. That tube has bores and the aboveconductors, the coolant will flow directly from the discharge openings along the conductors for cooling them.

Since the conductors are strapped to the tube of the socket which extends from the socket duct, and as disclosed and claimed in my copending application (D- 5599), the straps must not squeeze the feeder tubes and loop around them so that the feeder tubes extend outside of the strapped conductor assembly.

DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:

FIG. 1 illustrates a longitudinal section through a socket and end of a liquid cooled cable constructed in accordance with the preferred embodiment of the invention;

FIG. 2 is a section view along line 2-2 in FIG. 1; and

FIG. 3 is a section view of a sub-assembly of the assembly shown in FIG. 1.

Proceeding now to the detailed description of the drawings, the cable illustrated here is comprised of an inner tube 1, for example, a hose made of synthetic rubber, traded under the name Neopren. A plurality of stranded conductors 2 are disposed along and around the periphery of that tube 1. The tube and conductor assembly is enveloped by a rubber hose 3, preferably of the type which is reinforced by plies of fabric. Hose or tube 3 is essentially concentric to tube or hose 1, and the conductors occupy a portion of the ring or annular space between tubes 1 and 3.

Reference number 5 refers to a cable socket to which the various parts are connected. The socket has a main body 5a and a sleeve like extension 5b. Rubber hose or envelope 3 is connected to socket extension 5b by means of clamps 4 which are antimagnetic. The conductor ends are inserted into that extension 5b.

The hose 1 is held by a flexible sleeve 6 which in turn is held by a threaded connector 8, to which it is soldered. Connector 8 in turn is threaded in a tube 7 which extends from socket 5, in that the tube 7 is threaded into the socket body 5a at 9, well inside of sleeve extension 5b.

The socket 5, particularly main body 5a is a solid piece of forged metal with a central bore 10 and lateral ducts for running water to the cable. Bore l0 communicates with tube 7 and the important feature here is that the conductors 2 themselves will be enveloped by flowing water in the following manner.

As shown more specifically in FIG. 3, tube 7 has four radial (lateral) openings 16, and bent tubes 11 are soldered to tube 7 to run the water from the conduit path 10-7 so the annular space between tubes 1 and 3 containing the conductors. Particularly, these feeder tubes 11 extend radially from tube 7 in a star pattern and veer into axial direction along the general extension of the cable to discharge cooling fluid freely into the space between respective two conductors.

As can be seen best from FIG. 2, the axial ends of tubes 11 end inbetween respective two adjacent conductors 2. The Figure shows eight conductors 2 and four such tubes 11. Eight tubes 11 of like or smaller dimensions could be used instead. Size and number of tubes 11 employed depends to a considerable extent on the rate of coolant flow needed for a particular electrical power consumption by the cable.

Tubes 11 are made of metal, preferably copper or another heat proof material. The tubes 11 are brazed to tube 7 or otherwise connected thereto at the openings 16.

As can be seen from FIGS. 1 and 2, bores 12 are additionally provided in connector 8 for passing, additionally, water into the annular space between the inner and outer tubes 1 and 3 for cooling the conductors 2 by way of direct contact with these conductors. Thus, part of the coolant fed to duct 10 in socket 5 passes through these bores 12 and another part of the coolant is fed to the conductors through tubes 11. A cover or stop in tube 6 permits only a small portion of water to pass into tube 1. The cooling effect provided by the water in hose 1 is rather small and the water is used here primarily as stabilizer.

The construction of tube 7 is more readily derivable from FIG. 3. The tube has a corrugated exterior 13 to increase friction between it and the conductor 2, which are to be secured to that tube 7. The corrugations particularly prevent slippage of the conductors. Moreover, tube 7 has slightly widened axial ends for reasons which will be shown shortly.

Conceivably, tube 7 could be corrugated as a whole. However, it is preferred to use a basically straight wall tube in which corrugations have been machined through turning, milling or the like. This way, no flexibility is imparted upon the tube 7 which remains particularly stiff as against squeezingwhen the conductors are strapped thereto, as will be described shortly.

It should be noted, that the conductors 2 have a more radial outward disposition adjacent the thicker end portions 7a of tube 7 and they come close to the inner wall of socket sleeve 5b. Accordingly, the conductors are also radially spaced in these regions and here particularly, where the radial portions of feeder tubes 11 pass from tube 7 between respective two conductors, spread radially thereat accordingly. The circles 2a represent this displaced disposition.

Clamping straps 14 are particularly provided for fas tening the conductors to tube 7. These straps are preferably antimagnetic, and they clamp the conductors onto and against tube 7, so that they are maintained in position even under high tension. Particularly, these straps urge the conductors 2 into conformity with the outer contour of tube 7 and here particularly, the corrugated and radially recessed portion 13 thereof. The reason for using antimagnetic straps and clamps is to be seen in that interference should be avoided with the clamping action by strong electromagnetic fields emanating from the heavy current through the conductor.

Additionally, soft solder may be used to anchor the conductors 2 to tube 7 inside of socket sleeve and extension Sb. Please note, that the coolant flow exits from tubes 11 as well as openings 12 are located outside of socket 5, so that solder between parts 2 and 7 will not interfere with the coolant as discharged into the cable conductor space. Such low melting solder provides for additional fastening of the conductors to socket 5 inside of sleeve extension 5b.

Should solder run out for any reason, clamping straps 4 still hold all of the conductors to tube 7 quite firmly, so that they will not be pulled out. The straps 14 meander to some extent in that they loop around tubes 11 on the radial inside as far as the overall axis of the assembly is concerned, so that clamping and fastening action is not exerted upon the rather thin walled tubes 11; they will not be shut by squeezing.

The cable is assembled in the following manner. The sub-assembly shown inFIG. 3 is provided first, (except for threaded connector 8). Next, the cable conductors are placed on tube 7 and fastened thereto by means of clamp straps 14. The cable conductor ends are firmly positioned in that manner and it can readily be seen that this tube conductor sub-assembly can be tested as to strength against dislodgement upon pulling on the conductors.

Next, the threaded end of tube 7 (9) is threaded into socket body 5a so that the conductor ends will be positioned inside of socket sleeve 5b. The space between tube 7 and socket 5 is then filled with soft solder; usually this type of solder has a high tin content. Next, connector 8 with tube 6 soldered (brazed) thereto is threaded to the outer end of tube 7 and hose 1 is finally slipped onto tube 6. Conceivably clamps may be used here also.

The stranded conductors 2 are thereafter stranded as a whole about tube 1, whereupon the second socket is connected to the outer end of the cable. Next, outer tube 3 is provided onto the assembly, including heat protection and wear resistance layers and spacers. That part of the cable assembly is conventional. Finally, the outer tube 3 is secured, actually in water proof fashion, tothe outside of socket 5 by means of antimagnetic clamps and/or straps 4.

It should be noted, that the tubes 11 will not only serve for feeding coolant to the cable, but, at the other end and socket, liquid is discharged from the cable in the same fashion. Construction for discharge may not be that critical, but it is clearly economical to use the same kind of socket construction.

The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.

I claim:

1. Liquid cooled, heavy current cable having an inner tube, an outer tube and conductors inbetween the inner and outer tubes, further having a socket with a sleeve portion for receiving the ends of the conductors, the socket further provided with means for receiving cooling fluid and passing it to the interior of the sleeve portion, the improvement comprising a plurality of feeder tubes in the sleeve connected for receiving the said cooling fluid and passing it directly towards the space between the inner and outer tubes of the cable for flowing around the conductors in that space,

2. In a liquid cooled cable as in claim 1, wherein a particular tube extends in the sleeve of the socket and receives cooling fluid, and wherein the conductors are fastened to the particular tube, the feeder tubes being feeder tubes, the feeder tubes continuing axially for discharging fluid to the space between the conductors.

4. In a cable as in claim 3, wherein the feeder tubes extend axially beyond the sleeve.

* l= l l 

1. Liquid cooled, heavy current cable having an inner tube, an outer tube and conductors inbetween the inner and outer tubes, further having a socket with a sleeve portion for receiving the ends of the conductors, the socket further provided with means for receiving cooling fluid and passing it to the interior of the sleeve portion, the improvement comprising a plurality of feeder tubes in the sleeve connected for receiving the said cooling fluid and passing it directly towards the space between the inner and outer tubes of the cable for flowing around the conductors in that space.
 2. In a liquid cooled cable as in claim 1, wherein a particular tube extends in the sleeve of the socket and receives cooling fluid, and wherein the conductors are fastened to the particular tube, the feeder tubes being connected to said particular tube to receive the cooling fluid therefrom.
 3. In a cable as in claim 2, wherein the feeder tubes extend radially from the particular tube, the particular tube having lateral openings communicating with the feeder tubes, the feeder tubes continuing axially for discharging fluid to the space between the conductors.
 4. In a cable as in claim 3, wherein the feeder tubes extend axially beyond the sleeve. 